The present invention relates to an ultrasonic surgical apparatus for, for example, cutting, removing, or coagulating a living tissue, by an ultrasonic wave, while grasping the tissue either internally (inside a body) or externally.
This type of the ultrasonic surgical apparatus is known in U.S. Pat. No. 5,322,055 for example. The ultrasonic surgical apparatus comprises an ultrasonic wave transmitting probe member connected to an ultrasonic transducer, a sheath inserted through the probe member, a blade coupled to a forward end of the robe member, a jaw pivoted to a distal end of the sheath and facing the blade, and a handle provided on a proximal end of the sheath and adapted to swing the jaw through a rod. And the jaw is swung by the operation of the handle and, while grasping a living tissue between the jaw and the blade, an ultrasonic vibration is transmitted to the jaw and, by doing so, the living tissue is cut. At this time, simultaneous coagulating and cutting actions are applied by the ultrasonic wave to the grasped tissue and it is possible to cut off only the grasped tissue without bleeding in a patient.
Normally, this type of ultrasonic surgical apparatus can apply both the coagulating and cutting actions to the tissue by one operation and it is possible to rapidly cut open the tissue of the patient without bleeding. This procedure is simpler than the method for cutting the living tissue by an existing surgical knife. And attention has been paid to applying this method to the cases where the organs in the body cavity of the patient are treated, in particular, by a surgical operation under an endoscope.
With this ultrasonic surgical apparatus, the jaw opposite to the blade on the forward end of the probe is moved in swinging motion and the living tissue is grasped between the jaw and the blade and cut open while being coagulated. There is a risk, however, that, if the living tissue is forcibly squeezed between the jaw and the blade by operating the handle more strongly than normally, it will be simply mechanically cut off without being cut open while being coagulated with the ultrasonic wave. For example, the living tissue of the liver, etc., is liable to be readily cut off mechanically.
When even very narrow blood vessels are to be coagulated and cut off, it is difficult to control an amount of force with which the handle is operated. The control amount of force applied by the handle differs from individual to individual and lots of practice have been required in operating the handle with a constantly steady, proper control force.
In the case where, though depending upon the power extent of the ultrasonic transducer, the living tissue is grasped rather strongly between the blade and the jaw, the vibration of the probe may be suppressed and sometimes stopped.
Further, the action area of the blade is situated at the antinode loop of the ultrasonic vibration and located at a free end remote from the support area of the probe corresponding to the node of the ultrasonic vibration. For this reason, the blade area is naturally a ready-to-flex area. When the tissue is grasped with a force exceeding that required, then the blade area is greatly flexed in a direction escaping from the jaw, thus resulting in an inconvenient position in which the grasping surface of the blade and that of the jaw intersect with each other without being parallel to each other, that is, the jaw is diagonally opposite to the blade. When, in a final tissue cutting stage in particular, the jaw is diagonally opposite to the blade, these grasping surfaces cannot grasp the tissue uniformly, so that no proper cut of the tissue is expected. That is, some of the tissue remains uncut and it is not possible to coagulate/cut a whole tissue of interest at a time.